入力した数字を大文字にする

package com.wansha;

public class NumberTest {
	public String formateNubmer(String str)throws Exception{
		String sum = "";
		Integer in = 0;
		try{
			in = Integer.parseInt(str);
		}catch(NumberFormatException e){
			throw new Exception(" ");
		}
		String bitStr = "";
		boolean flag = false;
		for(int i = 0; i<str.length();i++){
			int Remainder = in%10;
			in/=10;
			if(Remainder == 0){
				if(!flag)continue;
				bitStr =changeUpperCase(Remainder);
				flag = false;
			}else{
				switch(i){
				case 0:
					bitStr = changeUpperCase(Remainder);
					flag = true;
					break;
				case 1:
					bitStr = changeUpperCase(Remainder)+" ";
					flag = true;
					break;
				case 2:
					bitStr = changeUpperCase(Remainder)+" ";
					flag = true;
					break;
				case 3:
					bitStr = changeUpperCase(Remainder)+" ";
					flag = true;
					break;
				case 4:
					bitStr = changeUpperCase(Remainder)+" ";
					flag = true;
					break;
				case 5:
					bitStr = changeUpperCase(Remainder)+" ";
					flag = true;
					break;
				case 6:
					bitStr = changeUpperCase(Remainder)+" ";
					flag = true;
					break;
				case 7:
					bitStr = changeUpperCase(Remainder)+" ";
					flag = true;
					break;
				case 8:
					bitStr = changeUpperCase(Remainder)+" ";
					flag = true;
					break;
				}
			}
			sum = bitStr +sum;
		}
		sum = sum.endsWith(" ")?sum.substring(0,sum.indexOf(" ")):sum;
		sum = sum.startsWith(" ")?sum.substring(sum.indexOf(" ")+1):sum;
		return sum;
	}
	public static void main(String[] args)throws Exception {
		args[0]="00000100";
		int k = Integer.parseInt(args[0]);
		if(null != args[0]){
			if(8<args[0].length())throw new Exception(" 8 ");
			NumberTest number = new NumberTest();
			String sum ;
			sum = number.formateNubmer(args[0]);
			System.out.println(sum);
		}
		
	}
	public String changeUpperCase(int i){
		String str = null;
		switch(i){
		case 0:
			str=" ";
			break;
		case 1:
			str=" ";
			break;
		case 2:
			str=" ";
			break;
		case 3:
			str=" ";
			break;
		case 4:
			str=" ";
			break;
		case 5:
			str=" ";
			break;
		case 6:
			str=" ";
			break;
		case 7:
			str=" ";
			break;
		case 8:
			str=" ";
			break;
		case 9:
			str=" ";
			break;
		}
		return str;
	}
}